E-screen assay validation: evaluation of estrogenic activity by MCF7 cell culture bioassay, in drinking water from different watersheds in state of Sao Paulo, Brazil

The speed of production and use of synthetic chemical products, since 1940, resulting in contamination ubiquitous of aquatic animals, land and the human population. Since 1960 observers noted an increase of changes in reproduction of animals across the globe as well as changes in reproduction and health of men by exposure to these synthetic products (VAN LABEKE et al, 2008) 

In 1991 scientists from various fields met at Wingspread Conference Center for defining and structuring the Disruption Endocrine phenomenon. These researchers, in consensus, established that many synthetic chemicals were potentially able to disrupt the endocrine system of animals and man. At that time concluded that the characterization of exposure to Endocrine Disruptors was a crucial aspect for the prognosis of health effects as given in the below link. (http://www.ourstolenfuture.org/Consensus/wingspread1.htm). 

In the mid-90s there was a clear insight the possible negative impact of endocrine disruptors and the need for new legislation to really ensure protection to human and animal’s health and the environment. But only two decades later the Society of Endocrinology renewed the request of the endocrine disruptors list and the effects of its exposure, considering as a priority research (DIAMANTI-KANDARAKIS et al, 2009). 

The welfare of society is linked to many chemicals, essential components to everyday life, which are found everywhere, even in remote locations both in the environment and animals and men. 

For millennia, human and animals’ bodies adapted to EDs vegetables, cereals and fruit (apple, cherry, plum, potato. Carrots, peas, beans, soybeans, wheat, oats, barley, rye, parsley, garlic) and naturally excreted not accumulate in the body. The chemicals, however, accumulate mainly in adipose tissue mimicking glandular hormones (Colborn etal, 2002). Some of these substances are transplacental and may affect the fetus as lead (Bowler and Cone, 2010) or fixate the milk being\ingested by the newborn (Matuo, 1999) even toxic agents already accumulated in the maternal organism over the years. (Colborn etal, 2002). 

Recent studies in several countries have shown that the aquatic environment can possess estrogenic activity capable of influencing the fauna. (Xeno) estrogens are believed to reach the aquatic environment mainly by means of municipal and industrial sewage outfalls. However, agricultural drainage may also be a route for (xeno) estrogens to enter the aquatic system. 

Numerous natural and anthropogenic substances are known to exhibit estrogenic activity. In the aquatic environment, estrogenic activity has primarily been ascribed to the natural steroids, 17b-estradiol (E2), estrone (E1) and estriol (E3), and the synthetic estrogen, ethinylestradiol (EE2), used in contraceptives and hormone replacement. To a lesser extent xenoestrogenic chemicals, such as alkylphenols and bisphenol A, may also contribute to the estrogenic activity in the aquatic environment. (GRAY et al, 2000, SHAW and MC CULLY, 2002; AERNI et al ,2004) 

Estrogen has been the endocrine disruptor most researched to be very active biologically and be the etiologic agent of diverse types of cancer and other conditions such as endometriosis, precocious puberty, feminization, masculinization, sterility (WELSHONS et al, 1999). Endocrine disruptors have recently been shown to promote an epigenetic transgenerational phenotype involving several disease states (e.g. male infertility) (GORE et al, 2013). The MCF-7 cell proliferation as say is potentially a simple and highly reproducible tool for the identification of estrogenic compounds. In the E-screen assay developed by SOTO etal. (1995), proliferation of MCF-7 cells as a response to estrogen is measured. The E-screen is based on the following three premises: (i) factors in human serum inhibit the proliferation of MCF-7 cells, (ii) estrogens induce cell proliferation by negating this inhibitory effect, and (iii) non-estrogenic steroids and growth factors do not neutralize the inhibitory signal present in human serum. 

Numerous studies on animal’s exposure of wildlife and laboratories such products have shown that endocrine disrupters affect various physiological processes such as brain activity, reproduction, immune response, development and metabolic rates. (Tyler, 1998; McLachlan, 2001; Guillette and Gunderson, 2001; Hayes etal., 2002; Markey etal., 2003).